Most annular blowout preventers offer some type of locking mechanism to facilitate quick changing of the blowout preventer sealing element. Existing designs include locking dogs or segments which are moved inwardly or outwardly by a tapered locking ring in a horizontal direction. These designs have the disadvantages of having a large number of individual segments which must be handled for assembling or removing the upper housing, some mechanisms are also open to admit debris which might interfere with the operation of the locking mechanism, and such designs do not provide for an adjustment in the position of the upper and lower housings relative to each other for compensating for variations in machining tolerances.
The present invention is directed to an improved locking mechanism for securing the upper housing of an annular blowout preventer to the lower housing for allowing for ease of replacement of the sealing element and overcoming the disadvantages of the prior art designs.